1. Field of Invention
The present invention relates to a molding die for use attached to an outlet of an extrusion-molding molding machine or such, and further relates to a method of molding a hollow molded article having a through-hole using such molding die.
2. Description of Related Art
There are various shapes of gas generating agents used in airbag apparatuses mounted in motor vehicles, and for example, cylindrical gas generating agents having a through-hole disclosed in JP-A No. 62-83406, JP-A No. 2002-31273 and JP-A No. 2000-94198 are known.
For the manufacturing of a cylindrical gas generating agent having a through-hole, a method of extrusion-molding by an attached die (base) 50, such as that shown in FIG. 8, to an outlet of an extrusion-molding molding machine, is employed.
The die 50 shown in FIG. 8 includes a pin plate 51 for connecting to the outlet of the extrusion-molding molding machine, a pin 52 attached perpendicularly to the surface of the pin plate 51, and a thick tubular bushing 53. The pin plate 51 has a material inflow port 54. The pin 52 is a rod-shaped pin of uniform diameter, and is disposed axially inside a material molding path 55 formed by the bushing 53. An outlet 56 of the die is provided in the extending-direction of the molding path 55.
Material which flows in from the inflow port 54 is, due to the existence of the pin 52, in the process of passing through the molding path 55 and being extruded from the outlet 56 of the die, extruded in the form of a string-shape or a rod-shape, having a through-hole with an inner diameter identical to that of the outer diameter of the pin 52. Furthermore, the string-shaped or rod-shaped molded article is cut at a desired length and a gas generating agent is obtained.